1. Field of the Invention
The present invention relates to an optical disk recorder having a function of erasing data in an optical disk.
2. Description of the Related Art
Conventionally, an optical disc recorder has a function for formatting an optical disc further to functions for writing data into the optical disc and reproducing the data recorded in the optical disc. The optical disc to which data are recordable includes write-once optical discs into which the data can be written only once and rewritable optical discs into which data can be rewritten repeatedly by a predetermined times. As for the write-once optical disc, CD-R (CD Recordable), DVD-R (DVD Recordable), DVD+R (DVD Recordable) are exemplified. Furthermore, as for the rewritable optical disc, CD-RW (CD Rewritable), DVD-RW (DVD Rewritable), DVD+RW (DVD Rewritable), DVD-RAM (DVD Random Access Memory) are exemplified.
In the rewritable optical disk, new data can be overwritten over data written on the disc and the data already written on the disc can be erased. When a user erases the data recorded on the optical disk, a picture which renders the user to confirm execution of erasure is displayed on a monitor screen connected to the optical disk recorder to which the optical disk inserted or a personal computer which mounts the optical disc recorder. When the user selects erasure, the data recorded on the optical disk is erased, so that the user cannot use the erased data again. Thus, when the user erases data by mistake or persons other than the user erase data intentionally or inadvertently, the user cannot use the erased data again.
Besides, a magneto optical disc, from which recorded data can be erased, has the same problem as that of the optical disc that the data recorded on the disc cannot be used after erasing the data.
Therefore, International Publication WO2002/035338 discloses a data recorder having a data saving function for saving transmitted data when the data is transmitted from a host computer to the data recorder so as to utilize the data after erasing the data. The data recorder records data into a magneto optical disc which needs to be erased the data already recorded before writing new data. When writing new data, the data recorder erases the data already recorded in the optical disc and simultaneously requires transmission of the new data to be recorded to the host computer. When data transmission error is detected in the data transmission from the host computer, if data corresponding to the data already erased were saved in a data saving medium, the data can be returned to the magneto optical disc. However, when the data erased from the magneto optical disc is not saved in another recording medium, the data erased cannot be returned to the magneto optical disc. Furthermore, the disc recorder needs a recording medium for storing the data transmitted from the host computer, so that cost of the disc recorder is increased. Still furthermore, if the user erroneously instructed to erase the data, the data erased cannot be returned to the magneto optical disc, again.
On the other hand, Japanese Laid-Open Patent Publication No. 2003-263840 discloses a disc recorder which records data already recorded in an optical disc or a magneto optical disc into a backup memory provided in a disc cartridge when an electric power of the recorder is switched on. When error occurs in data writing, the data stored in the backup is rewritten into the optical disc or the magneto optical disc, thereby returning the backup data into to the optical disc or the magneto optical disc. Subsequently, new data to be recorded are further recorded into the optical disc or the magneto optical disc. However, when the data were erased according to the instruction by the user, the data erased cannot be returned to the optical disc or the magneto optical disc.
Japanese Laid-Open Patent Publication No. 2000-036161 discloses a recording medium which stores overwrite protection information for preventing undesired overwriting or erasing of the data recorded on the recording medium. The recording medium has a step for checking whether the overwrite protection information exists or not when writing or erasing the data, and restricts to write or erase the data on the recording medium corresponding to the overwrite protection information. However, when the data were erased according to the instruction by the user, the data erased cannot be returned to the recording medium.